1. Field of the Invention
This invention relates to pinch type flow control valves that restrict fluid flow either in a pipeline or at the end of a pipeline.
2. Description of Related Art
Conventional pinch valves consist of either a single tubular “sleeve” or a “combined sleeve” consisting of two “half-sleeves” mechanically joined on the horizontal centerline. When the valve is operated by applying air pressure between the outside of the sleeve and the inside of the valve body, the sleeve is squeezed toward the centerline of the valve. This squeezing action typically occurs from two opposite sides.
Closing the valve, either partially or fully, limits the flow of water through the attached piping. The valve can be adjusted to achieve the desired flow by adjusting the operating air pressure.
In a conventional pinch valve, the sleeve closes from two opposite sides at the same time. This produces a specific throttling action for a specific amount of operating air pressure. If only one side of the sleeve is closed, the sensitivity to operating air pressure is less, that is, it requires more sleeve motion (which requires more air pressure) to reduce the flow by the same amount.
It is an object of the present invention to provide improved control of fluid flow at reduced cost. By having the valve pinching action only from one side of the valve, the sleeve does not need to be fully circular. It can be a “half-sleeve” pinching only from one side against the opposite valve body wall. A half-sleeve is less costly to manufacture.